/* * DHCP library with GLib integration * * Copyright (C) 2007-2012 Intel Corporation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * */ #ifdef HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include "gdhcp.h" #include "common.h" static const DHCPOption client_options[] = { { OPTION_IP, 0x01 }, /* subnet-mask */ { OPTION_IP | OPTION_LIST, 0x03 }, /* routers */ { OPTION_IP | OPTION_LIST, 0x06 }, /* domain-name-servers */ { OPTION_STRING, 0x0c }, /* hostname */ { OPTION_STRING, 0x0f }, /* domain-name */ { OPTION_IP | OPTION_LIST, 0x2a }, /* ntp-servers */ { OPTION_U32, 0x33 }, /* dhcp-lease-time */ /* Options below will not be exposed to user */ { OPTION_IP, 0x32 }, /* requested-ip */ { OPTION_U8, 0x35 }, /* message-type */ { OPTION_U32, 0x36 }, /* server-id */ { OPTION_U16, 0x39 }, /* max-size */ { OPTION_STRING, 0x3c }, /* vendor */ { OPTION_STRING, 0x3d }, /* client-id */ { OPTION_STRING, 0xfc }, /* UNOFFICIAL proxy-pac */ { OPTION_UNKNOWN, 0x00 }, }; GDHCPOptionType dhcp_get_code_type(uint8_t code) { int i; for (i = 0; client_options[i].code; i++) { if (client_options[i].code == code) return client_options[i].type; } return OPTION_UNKNOWN; } uint8_t *dhcp_get_option(struct dhcp_packet *packet, int code) { int len, rem; uint8_t *optionptr; uint8_t overload = 0; /* option bytes: [code][len][data1][data2]..[dataLEN] */ optionptr = packet->options; rem = sizeof(packet->options); while (1) { if (rem <= 0) /* Bad packet, malformed option field */ return NULL; if (optionptr[OPT_CODE] == DHCP_PADDING) { rem--; optionptr++; continue; } if (optionptr[OPT_CODE] == DHCP_END) { if (overload & FILE_FIELD) { overload &= ~FILE_FIELD; optionptr = packet->file; rem = sizeof(packet->file); continue; } else if (overload & SNAME_FIELD) { overload &= ~SNAME_FIELD; optionptr = packet->sname; rem = sizeof(packet->sname); continue; } break; } len = 2 + optionptr[OPT_LEN]; rem -= len; if (rem < 0) continue; /* complain and return NULL */ if (optionptr[OPT_CODE] == code) return optionptr + OPT_DATA; if (optionptr[OPT_CODE] == DHCP_OPTION_OVERLOAD) overload |= optionptr[OPT_DATA]; optionptr += len; } return NULL; } int dhcp_end_option(uint8_t *optionptr) { int i = 0; while (optionptr[i] != DHCP_END) { if (optionptr[i] != DHCP_PADDING) i += optionptr[i + OPT_LEN] + OPT_DATA - 1; i++; } return i; } /* get a rough idea of how long an option will be */ static const uint8_t len_of_option_as_string[] = { [OPTION_IP] = sizeof("255.255.255.255 "), [OPTION_STRING] = 1, [OPTION_U8] = sizeof("255 "), [OPTION_U16] = sizeof("65535 "), [OPTION_U32] = sizeof("4294967295 "), }; static int sprint_nip(char *dest, const char *pre, const uint8_t *ip) { return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]); } /* Create "opt_value1 option_value2 ..." string */ char *malloc_option_value_string(uint8_t *option, GDHCPOptionType type) { unsigned upper_length; int len, optlen; char *dest, *ret; len = option[OPT_LEN - OPT_DATA]; type &= OPTION_TYPE_MASK; optlen = dhcp_option_lengths[type]; if (optlen == 0) return NULL; upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen); dest = ret = g_malloc(upper_length + 1); if (ret == NULL) return NULL; while (len >= optlen) { switch (type) { case OPTION_IP: dest += sprint_nip(dest, "", option); break; case OPTION_U16: { uint16_t val_u16 = get_be16(option); dest += sprintf(dest, "%u", val_u16); break; } case OPTION_U32: { uint32_t val_u32 = get_be32(option); dest += sprintf(dest, "%u", val_u32); break; } case OPTION_STRING: memcpy(dest, option, len); dest[len] = '\0'; return ret; default: break; } option += optlen; len -= optlen; if (len <= 0) break; *dest++ = ' '; *dest = '\0'; } return ret; } uint8_t *dhcpv6_get_option(struct dhcpv6_packet *packet, uint16_t pkt_len, int code, uint16_t *option_len, int *option_count) { int rem, count = 0; uint8_t *optionptr, *found = NULL; uint16_t opt_code, opt_len, len; optionptr = packet->options; rem = pkt_len - 1 - 3; if (rem <= 0) goto bad_packet; while (1) { opt_code = optionptr[0] << 8 | optionptr[1]; opt_len = len = optionptr[2] << 8 | optionptr[3]; len += 2 + 2; /* skip code and len */ if (len < 4) goto bad_packet; rem -= len; if (rem < 0) break; if (opt_code == code) { if (option_len != NULL) *option_len = opt_len; if (rem < 0) goto bad_packet; else found = optionptr + 2 + 2; count++; } if (rem == 0) break; optionptr += len; } if (option_count != NULL) *option_count = count; return found; bad_packet: if (option_len != NULL) *option_len = 0; if (option_count != NULL) *option_count = 0; return NULL; } uint8_t *dhcpv6_get_sub_option(unsigned char *option, uint16_t max_len, uint16_t *option_code, uint16_t *option_len) { int rem; uint16_t code, len; rem = max_len - 2 - 2; if (rem <= 0) /* Bad option */ return NULL; code = option[0] << 8 | option[1]; len = option[2] << 8 | option[3]; rem -= len; if (rem < 0) return NULL; *option_code = code; *option_len = len; return &option[4]; } /* * Add an option (supplied in binary form) to the options. * Option format: [code][len][data1][data2]..[dataLEN] */ void dhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) { unsigned len; uint8_t *optionptr = packet->options; unsigned end = dhcp_end_option(optionptr); len = OPT_DATA + addopt[OPT_LEN]; /* end position + (option code/length + addopt length) + end option */ if (end + len + 1 >= DHCP_OPTIONS_BUFSIZE) /* option did not fit into the packet */ return; memcpy(optionptr + end, addopt, len); optionptr[end + len] = DHCP_END; } /* * Add an option (supplied in binary form) to the options. * Option format: [code][len][data1][data2]..[dataLEN] */ void dhcpv6_add_binary_option(struct dhcpv6_packet *packet, uint16_t max_len, uint16_t *pkt_len, uint8_t *addopt) { unsigned len; uint8_t *optionptr = packet->options; len = 2 + 2 + (addopt[2] << 8 | addopt[3]); /* end position + (option code/length + addopt length) */ if (*pkt_len + len >= max_len) /* option did not fit into the packet */ return; memcpy(optionptr + *pkt_len, addopt, len); *pkt_len += len; } static GDHCPOptionType check_option(uint8_t code, uint8_t data_len) { GDHCPOptionType type = dhcp_get_code_type(code); uint8_t len; if (type == OPTION_UNKNOWN) return type; len = dhcp_option_lengths[type & OPTION_TYPE_MASK]; if (len != data_len) { printf("Invalid option len %d (expecting %d) for code 0x%x\n", data_len, len, code); return OPTION_UNKNOWN; } return type; } void dhcp_add_option_uint32(struct dhcp_packet *packet, uint8_t code, uint32_t data) { uint8_t option[6]; if (check_option(code, sizeof(data)) == OPTION_UNKNOWN) return; option[OPT_CODE] = code; option[OPT_LEN] = sizeof(data); put_be32(data, option + OPT_DATA); dhcp_add_binary_option(packet, option); return; } void dhcp_add_option_uint16(struct dhcp_packet *packet, uint8_t code, uint16_t data) { uint8_t option[6]; if (check_option(code, sizeof(data)) == OPTION_UNKNOWN) return; option[OPT_CODE] = code; option[OPT_LEN] = sizeof(data); put_be16(data, option + OPT_DATA); dhcp_add_binary_option(packet, option); return; } void dhcp_add_option_uint8(struct dhcp_packet *packet, uint8_t code, uint8_t data) { uint8_t option[6]; if (check_option(code, sizeof(data)) == OPTION_UNKNOWN) return; option[OPT_CODE] = code; option[OPT_LEN] = sizeof(data); option[OPT_DATA] = data; dhcp_add_binary_option(packet, option); return; } void dhcp_init_header(struct dhcp_packet *packet, char type) { memset(packet, 0, sizeof(*packet)); packet->op = BOOTREQUEST; switch (type) { case DHCPOFFER: case DHCPACK: case DHCPNAK: packet->op = BOOTREPLY; } packet->htype = 1; packet->hlen = 6; packet->cookie = htonl(DHCP_MAGIC); packet->options[0] = DHCP_END; dhcp_add_option_uint8(packet, DHCP_MESSAGE_TYPE, type); } void dhcpv6_init_header(struct dhcpv6_packet *packet, uint8_t type) { int id; memset(packet, 0, sizeof(*packet)); packet->message = type; id = random(); packet->transaction_id[0] = (id >> 16) & 0xff; packet->transaction_id[1] = (id >> 8) & 0xff; packet->transaction_id[2] = id & 0xff; } static gboolean check_vendor(uint8_t *option_vendor, const char *vendor) { uint8_t vendor_length = sizeof(vendor) - 1; if (option_vendor[OPT_LEN - OPT_DATA] != vendor_length) return FALSE; if (memcmp(option_vendor, vendor, vendor_length) != 0) return FALSE; return TRUE; } static void check_broken_vendor(struct dhcp_packet *packet) { uint8_t *vendor; if (packet->op != BOOTREQUEST) return; vendor = dhcp_get_option(packet, DHCP_VENDOR); if (vendor == NULL) return; if (check_vendor(vendor, "MSFT 98") == TRUE) packet->flags |= htons(BROADCAST_FLAG); } int dhcp_recv_l3_packet(struct dhcp_packet *packet, int fd) { int n; memset(packet, 0, sizeof(*packet)); n = read(fd, packet, sizeof(*packet)); if (n < 0) return -errno; if (packet->cookie != htonl(DHCP_MAGIC)) return -EPROTO; check_broken_vendor(packet); return n; } int dhcpv6_recv_l3_packet(struct dhcpv6_packet **packet, unsigned char *buf, int buf_len, int fd) { int n; n = read(fd, buf, buf_len); if (n < 0) return -errno; *packet = (struct dhcpv6_packet *)buf; return n; } /* TODO: Use glib checksum */ uint16_t dhcp_checksum(void *addr, int count) { /* * Compute Internet Checksum for "count" bytes * beginning at location "addr". */ int32_t sum = 0; uint16_t *source = (uint16_t *) addr; while (count > 1) { /* This is the inner loop */ sum += *source++; count -= 2; } /* Add left-over byte, if any */ if (count > 0) { /* Make sure that the left-over byte is added correctly both * with little and big endian hosts */ uint16_t tmp = 0; *(uint8_t *) &tmp = *(uint8_t *) source; sum += tmp; } /* Fold 32-bit sum to 16 bits */ while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16); return ~sum; } #define IN6ADDR_ALL_DHCP_RELAY_AGENTS_AND_SERVERS_MC_INIT \ { { { 0xff,0x02,0,0,0,0,0,0,0,0,0,0,0,0x1,0,0x2 } } } /* ff02::1:2 */ static const struct in6_addr in6addr_all_dhcp_relay_agents_and_servers_mc = IN6ADDR_ALL_DHCP_RELAY_AGENTS_AND_SERVERS_MC_INIT; /* from netinet/in.h */ struct in6_pktinfo { struct in6_addr ipi6_addr; /* src/dst IPv6 address */ unsigned int ipi6_ifindex; /* send/recv interface index */ }; int dhcpv6_send_packet(int index, struct dhcpv6_packet *dhcp_pkt, int len) { struct msghdr m; struct iovec v; struct in6_pktinfo *pktinfo; struct cmsghdr *cmsg; int fd, ret; struct sockaddr_in6 dst; void *control_buf; size_t control_buf_len; fd = socket(PF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP); if (fd < 0) return -errno; memset(&dst, 0, sizeof(dst)); dst.sin6_family = AF_INET6; dst.sin6_port = htons(DHCPV6_SERVER_PORT); dst.sin6_addr = in6addr_all_dhcp_relay_agents_and_servers_mc; control_buf_len = CMSG_SPACE(sizeof(struct in6_pktinfo)); control_buf = g_try_malloc0(control_buf_len); if (control_buf == NULL) { close(fd); return -ENOMEM; } memset(&m, 0, sizeof(m)); memset(&v, 0, sizeof(v)); m.msg_name = &dst; m.msg_namelen = sizeof(dst); v.iov_base = (char *)dhcp_pkt; v.iov_len = len; m.msg_iov = &v; m.msg_iovlen = 1; m.msg_control = control_buf; m.msg_controllen = control_buf_len; cmsg = CMSG_FIRSTHDR(&m); cmsg->cmsg_level = IPPROTO_IPV6; cmsg->cmsg_type = IPV6_PKTINFO; cmsg->cmsg_len = CMSG_LEN(sizeof(*pktinfo)); pktinfo = (struct in6_pktinfo *)CMSG_DATA(cmsg); memset(pktinfo, 0, sizeof(*pktinfo)); pktinfo->ipi6_ifindex = index; m.msg_controllen = cmsg->cmsg_len; ret = sendmsg(fd, &m, 0); if (ret < 0) perror("DHCPv6 msg send failed"); g_free(control_buf); close(fd); return ret; } int dhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt, uint32_t source_ip, int source_port, uint32_t dest_ip, int dest_port, const uint8_t *dest_arp, int ifindex) { struct sockaddr_ll dest; struct ip_udp_dhcp_packet packet; int fd, n; enum { IP_UPD_DHCP_SIZE = sizeof(struct ip_udp_dhcp_packet) - EXTEND_FOR_BUGGY_SERVERS, UPD_DHCP_SIZE = IP_UPD_DHCP_SIZE - offsetof(struct ip_udp_dhcp_packet, udp), }; fd = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IP)); if (fd < 0) return -errno; memset(&dest, 0, sizeof(dest)); memset(&packet, 0, sizeof(packet)); packet.data = *dhcp_pkt; dest.sll_family = AF_PACKET; dest.sll_protocol = htons(ETH_P_IP); dest.sll_ifindex = ifindex; dest.sll_halen = 6; memcpy(dest.sll_addr, dest_arp, 6); if (bind(fd, (struct sockaddr *)&dest, sizeof(dest)) < 0) { close(fd); return -errno; } packet.ip.protocol = IPPROTO_UDP; packet.ip.saddr = source_ip; packet.ip.daddr = dest_ip; packet.udp.source = htons(source_port); packet.udp.dest = htons(dest_port); /* size, excluding IP header: */ packet.udp.len = htons(UPD_DHCP_SIZE); /* for UDP checksumming, ip.len is set to UDP packet len */ packet.ip.tot_len = packet.udp.len; packet.udp.check = dhcp_checksum(&packet, IP_UPD_DHCP_SIZE); /* but for sending, it is set to IP packet len */ packet.ip.tot_len = htons(IP_UPD_DHCP_SIZE); packet.ip.ihl = sizeof(packet.ip) >> 2; packet.ip.version = IPVERSION; packet.ip.ttl = IPDEFTTL; packet.ip.check = dhcp_checksum(&packet.ip, sizeof(packet.ip)); /* * Currently we send full-sized DHCP packets (zero padded). * If you need to change this: last byte of the packet is * packet.data.options[dhcp_end_option(packet.data.options)] */ n = sendto(fd, &packet, IP_UPD_DHCP_SIZE, 0, (struct sockaddr *) &dest, sizeof(dest)); close(fd); if (n < 0) return -errno; return n; } int dhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt, uint32_t source_ip, int source_port, uint32_t dest_ip, int dest_port) { struct sockaddr_in client; int fd, n, opt = 1; enum { DHCP_SIZE = sizeof(struct dhcp_packet) - EXTEND_FOR_BUGGY_SERVERS, }; fd = socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP); if (fd < 0) return -errno; setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); memset(&client, 0, sizeof(client)); client.sin_family = AF_INET; client.sin_port = htons(source_port); client.sin_addr.s_addr = htonl(source_ip); if (bind(fd, (struct sockaddr *) &client, sizeof(client)) < 0) { close(fd); return -errno; } memset(&client, 0, sizeof(client)); client.sin_family = AF_INET; client.sin_port = htons(dest_port); client.sin_addr.s_addr = htonl(dest_ip); if (connect(fd, (struct sockaddr *) &client, sizeof(client)) < 0) { close(fd); return -errno; } n = write(fd, dhcp_pkt, DHCP_SIZE); close(fd); if (n < 0) return -errno; return n; } int dhcp_l3_socket(int port, const char *interface, int family) { int fd, opt = 1, len; struct sockaddr_in addr4; struct sockaddr_in6 addr6; struct sockaddr *addr; fd = socket(family, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP); if (fd < 0) return -errno; setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)); if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, interface, strlen(interface) + 1) < 0) { close(fd); return -1; } if (family == AF_INET) { memset(&addr4, 0, sizeof(addr4)); addr4.sin_family = family; addr4.sin_port = htons(port); addr = (struct sockaddr *)&addr4; len = sizeof(addr4); } else if (family == AF_INET6) { memset(&addr6, 0, sizeof(addr6)); addr6.sin6_family = family; addr6.sin6_port = htons(port); addr = (struct sockaddr *)&addr6; len = sizeof(addr6); } else { close(fd); return -EINVAL; } if (bind(fd, addr, len) != 0) { close(fd); return -1; } return fd; } char *get_interface_name(int index) { struct ifreq ifr; int sk, err; if (index < 0) return NULL; sk = socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0); if (sk < 0) { perror("Open socket error"); return NULL; } memset(&ifr, 0, sizeof(ifr)); ifr.ifr_ifindex = index; err = ioctl(sk, SIOCGIFNAME, &ifr); if (err < 0) { perror("Get interface name error"); close(sk); return NULL; } close(sk); return g_strdup(ifr.ifr_name); } gboolean interface_is_up(int index) { int sk, err; struct ifreq ifr; gboolean ret = FALSE; sk = socket(PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0); if (sk < 0) { perror("Open socket error"); return FALSE; } memset(&ifr, 0, sizeof(ifr)); ifr.ifr_ifindex = index; err = ioctl(sk, SIOCGIFNAME, &ifr); if (err < 0) { perror("Get interface name error"); goto done; } err = ioctl(sk, SIOCGIFFLAGS, &ifr); if (err < 0) { perror("Get interface flags error"); goto done; } if (ifr.ifr_flags & IFF_UP) ret = TRUE; done: close(sk); return ret; }